This amendment of the principal Act again sharpens criteria of regulating mineral charges in order to better protect water against pollution by nitrates, raises mineral charges, and prescribes rules for the size of production of manure on farms. The maximum allowed quantity of manure production depends now on the possibility and capacity of producers to use such manure on their own land or to place upon the market through so-called fertilizer sale-purchase agreements. Another criteria for production is the "fertilizer storage capacity". No farm shall produce more manure in a given year than its storage capacity increased by 15 percent in that year.